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🔗 https://leetcode.com/problems/maximum-difference-between-even-and-odd-frequency-i

题目

• 给一个由小写字母组成的字符串
• 返回 freq(ch1) - freq(ch2) 的最大值，要求 ch1 出现次数为 odd，ch2 出现次数为 even

思路

• 遍历字符串，统计字符的频率
• 记录 max odd 的频率，min even 的频率，注意不统计 0
• 返回 max_odd - min_even

代码

class Solution {
public:int maxDifference(string s) {vector<int> freq(26);for (auto ch : s) {freq[ch - 'a']++;}int max_odd = 0;int min_even = s.size();for (int i = 0; i < 26; i++) {if (freq[i] == 0) continue;if (freq[i] & 1) {max_odd = max(max_odd, freq[i]);} else {min_even = min(min_even, freq[i]);}}return max_odd - min_even;}
};